umount -l /nfsbackup Cannot create link /etc/mtab~ Perhaps there is a stale lock file?

Getting the following error while trying to umount a NFS mount?

root@# umount -l /nfsbackup

Cannot create link /etc/mtab~

Perhaps there is a stale lock file?

Please check whether there is temp files with the name /etc/mtab.tmp and /etc/mtab~ . Deleting these files will solve the problem. These files are either left over from a reboot or created accidentally.

~Sanil